Maryland Geological Survey 297 



They owe this comparison with the latter to a considerable extent to 

 the presence of adventitious roots as in Angioptens where these roots 

 originate near the top of the stem and grow downward through the 

 cortical tissue. Again in the late Paleozoic Psaronius steins there are a 

 mass of closely packed roots separated from the true vascular region by 

 a zone of sclerenchyma, the whole enclosed in a true cortex. In the latter 

 some of the steles are cauline and some are common while in T empultya 

 they are apparently all common, and Tempshya diifers froiu all other 

 known forms in the singular interlacing course of the steles. Their 

 course has, however, not as yet been made out with certainty. 



The Potomac material while abundant is poorly preserved and is in- 

 teresting chiefly as the first record of this singular type of fern from 

 North America. 



Seward ^ discussed the genus at length in 1894 and followed Feist- 

 mantel (1872) and Solms-Laubach (1891) in regarding Tempshya as 

 a condition of preservation of fern stems rather than as a precise term for 

 a distinct type. There can be no doubt but that the Maryland forjns are 

 a distinct type or that they are not generically different from the Wealden 

 forms. They are not portions of fern stems ahove the stem apex, as 

 Corda suggests, nor basal parts of stems as Stenzel suggests, neither have 

 they lost their vascular cylinder during fossilization, nor are they rhizomes 

 creeping among the felted roots of a Protopteris stem. The Maryland 

 material is abundant and the stems are all nearly circular in cross-sec- 

 tion. While the preservation is too poor for histological detail it is good 

 enough to show that there never was a distinct central vascular cylinder, 

 despite the fact that both Feistmantel and Velenovsky consider certain 

 specimens of Tempshya as having such a cylinder of the Protopteris 

 type. Unfortunately all of the Maryland material, and the European 

 also according to Seward, is porous and imperfectly preserved. 



Tempshya is common in Maryland and in the Wealden, and Velen- 

 ovsky speaks of examining over 100 specimens from the Quader of 

 Bohemia. 



^ Seward. Wealden Fl., pt. i, 1894, pp. 148-159. 



